/Engine/Source/Runtime/Landscape/Classes/LandscapeProxy.h
Get the list of grass types on this landscape
static void GetGrassTypes ( const [UWorld](API\Runtime\Engine\Engine\UWorld) * World, [UMaterialInterface](API\Runtime\Engine\Materials\UMaterialInterface) * LandscapeMat, [TArray](API\Runtime\Core\Containers\TArray)< [ULandscapeGrassType](API\Runtime\Landscape\ULandscapeGrassType) * > & GrassTypesOut, float & OutMaxDiscardDistance )